The present invention relates to the field of electro-optical components, and more particularly, to protective coatings therefor.
The ever increasing usage of the Internet, teleconferencing, etc. are driving the need for faster methods of data communication that can handle high bandwidth signal transfer. Optical communication, such as through the use of photonics over fiber optic networks, for example, is one communication method which is becoming more prevalent as a result.
With the development and implementation of optical communications networks has come the need for smaller and more reliable optical components. For example, electro-optical components such as micro-optoelectromechanical systems (MOEMS) are now being produced for switching and routing photonic broadband data streams. Yet, a MOEMS may require several million mirrors or more to be used in certain optical networks. Such components must be reliable and able to operate in hostile environmental conditions which may otherwise degrade mirrors, switches, and optical performance, as well as the mechanical operation of hinges, address and landing electrodes on such components.
Accordingly, packaging is an important consideration in the manufacture of MOEMS and other miniaturized electro-optical components. Such packaging typically needs to protect the component from atmospheric contaminants such as moisture and subatomic particles. As a result, the component may require a protective coating to reduce occurrences of corrosion or stiction caused by water vapor, for example. Typical prior art coatings include those produced by inorganic chemical vapor deposition (e.g., MgF2, MgPO4, SiN, SiON, SIF4), parylene type N, C, D, and F silicones (such as DC 1900 manufactured by the Dow Chemical Company of Midland, Mich.), and fluoroacrylics (such as FC-722 manufactured by the Minnesota Mining and Manufacturing Company of St. Paul, Minn.).
Unfortunately, the above prior art coatings typically suffer from one or more drawbacks such as high cost, reliability, and the inability to allow re-working of the component. Further, such coatings may not be able to provide non-hermetic and conformal coatings, which may be required in certain applications.
One promising coating material which has been used in various large scale applications to address these drawbacks is fluorinated poly(phenylene ether ketone), or 12F-PEK. This material is disclosed in U.S. Pat. No. 4,902,769 to Cassidy et al, which is hereby incorporated herein in its entirety by reference. By way of example, an article entitled Fluorinated Poly(Phenylene Ether Ketones) by St. Clair et al. (NASA Tech Brief, November 1994, vol. 18, Issue 11, page 74) notes that 1.2F-PEK may be well suited for use as film and coating material in electronic and thermal-control applications. More specifically, the article lists such applications as passivant insulating coats and interlevel dielectrics in microelectronic circuits, or as protective transparent coats on solar cells or mirrors.
The above article further notes that 12F-PEK is a colorless, transparent, and has a low-dielectric constant. Even so, 12F-PEK may still not be sufficiently transparent for use with MOEMS and other miniaturized electro-optical components.
In view of the foregoing background, it is therefore an object of the invention to provide an electro-optical component including a protective coating and associated methods that provides adequate transparency, reliability, and that allows for re-working of the electro-optical component.
This and other objects, features, and advantages in accordance with the present invention are provided by a method for applying a protective coating to an electro-optical component including positioning the electro-optical component in a chamber and applying a coating composition to at least one surface of the electro-optical component to form the protective coating. The coating composition may include fluorinated poly(phenylene ether ketone) and an anti-reflection agent. The coating composition may further include a solvent for facilitating the application thereof.
More specifically, applying the coating composition may include at least one of spray coating and spin coating. In particular, the chamber may be a vacuum chamber, for example, and the vacuum chamber may be evacuated and the electro-optical component spray coated therein. Preferably, the coating composition is applied to form a conformal protective coating on substantially the entire at least one surface.
Furthermore, the anti-reflection agent may include at least one of an inorganic salt, an organofunctionalized additive, and an erbium dopant. A thickness of the protective coating may be less than about 25 xcexcm, for example. Additionally, the electro-optical component may include at least one of a micro-optoelectromechanical system (MOEMS), a vertical-cavity surface-emitting laser (VCSEL), an optical switch, a mirror array, an optic router, an optical wavelength conditioner, an optical transmitter, an optical receiver, an optical transceiver, a laser diode, a holographic grating, a diffraction grating, and a lens. The at least one surface of the electro-optical component may also be non-planar.
The method may further include cleaning the at least one surface prior to applying the coating composition and heating the electro-optical component during application of the coating composition. More particularly, the heating may be performed at a temperature in a range of about 25 to 100xc2x0 C. Additionally, the protective coating of the electro-optical component may be cured in the chamber for a predetermined time and at a predetermined temperature.
Another method aspect of the invention is for re-working an electro-optical component including a 12F-PEK protective coating thereon. The method may include removing the 12F-PEK protective coating to expose at least one portion of the electro-optical component, and applying a coating composition including 12F-PEK to the at least one exposed portion of the electro-optical component. The coating composition and its application may be similar to that described above.
An electro-optical component according to the invention includes a substrate and at least one electro-optical device thereon, and a protective coating on the substrate and the at least one electro-optical device comprising fluorinated poly(phenylene ether ketone) and an anti-reflection agent. The anti-reflection agent may include at least one of an inorganic salt, an organofunctionalized additive, and an erbium dopant. The protective coating may have a thickness of less than about 3 xcexcm, for example.
Further, the at least one electro-optical device may have a non-planar surface, and the protective coating may substantially cover the non-planar surface. Also, the electro-optical device may be at least one of a micro-optoelectromechanical system (MOEMS), a vertical-cavity surface-emitting laser (VCSEL), an optical switch, a mirror array, an optic router, an optical wavelength conditioner, an optical transmitter, an optical receiver, an optical transceiver, a laser diode, a holographic grating, a diffraction grating, and a lens.
A coating for an electro-optical component according to the invention is also provided. The coating may include a solvent, fluorinated poly(phenylene ether ketone), and an anti-reflection agent. More specifically, the coating may include about 2 to 8.5% by weight of the fluorinated poly(phenylene ether ketone) and about 1.0 to 6.0% by weight of the anti-reflection agent. Further, the anti-reflection agent may include at least one of an inorganic salt, an organofunctionalized additive, and an erbium dopant.